o-Cresol

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o-Cresol
Kekulé, skeletal formula of o-cresol with some implicit hydrogens shown
Spacefill model of o-cresol
Names
Preferred IUPAC name
2-Methylphenol
Systematic IUPAC name
2-Methylbenzenol
Other names
2-Cresol
o-Cresol
ortho-Cresol
2-Hydroxytoluene
o-Cresylic acid
1-Hydroxy-2-methylbenzene
Identifiers
3D model (JSmol)
3DMet
506917
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.204 Edit this at Wikidata
EC Number
  • 202-423-8
101619
KEGG
MeSH 2-Cresol
RTECS number
  • GO6300000
UNII
UN number 2076, 3455
  • InChI=1S/C7H8O/c1-6-4-2-3-5-7(6)8/h2-5,8H,1H3 checkY
    Key: QWVGKYWNOKOFNN-UHFFFAOYSA-N ☒N
  • Cc1ccccc1O
Properties
C7H8O
Molar mass 108.140 g·mol−1
Appearance Colorless to white crystals
Odor sweet, phenolic odor
Density 1.0465 g cm−3
Melting point 31 °C; 88 °F; 304 K
Boiling point 191 °C; 376 °F; 464 K
31 g dm−3 (at 40 °C)
Solubility soluble in chloroform, ether, CCl4
Solubility in ethanol Miscible (at 30 °C)
Solubility in diethyl ether Miscible (at 30 °C)
log P 1.962
Vapor pressure 40 Pa (at 20 °C)
Acidity (pKa) 10.316
Basicity (pKb) 3.681
−72.9×10−6 cm3/mol
1.5353
Viscosity 35.06 cP (at 45 °C)
Thermochemistry
154.56 J K−1 mol−1
165.44 J K−1 mol−1
Std enthalpy of
formation (ΔfH⦵298)
 −204.3 kJ mol−1
Std enthalpy of
combustion (ΔcH⦵298)
 −3.6936 MJ mol−1
Hazards
Safety data sheet External MSDS
GHS labelling:
GHS05: CorrosiveGHS06: Toxic
Signal word
 Danger
H301, H311, H314
P260, P264, P270, P280, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P322, P330, P361, P363, P405, P501
NFPA 704 (fire diamond)
3
2
0
Flash point 81 °C (178 °F; 354 K)
598.9 °C (1,110.0 °F; 872.0 K)
Explosive limits 1.4%–? (148 °C)[1]
Lethal dose or concentration (LD, LC):
LD50 (median dose)
 1350 mg/kg (rat, oral)
121 mg/kg (rat, oral)
344 mg/kg (mouse, oral)[2]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 5 ppm (22 mg/m3) [skin][1]
REL (Recommended)
 TWA 2.3 ppm (10 mg/m3)[1]
IDLH (Immediate danger)
 250 ppm[1]
Related compounds
Related phenols
 m-cresol, p-cresol, phenol
Except where otherwise noted, data are given for materials in their standard state (at 25 ��C [77 °F], 100 kPa).
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Infobox references

ortho-Cresol, also called 2-methylphenol, or 2-hydroxytoluene, is an organic compound with the formula CH3C6H4(OH). It is a colourless solid that is widely used intermediate in the production of other chemicals. It is a derivative of phenol and is an isomer of p-cresol and m-cresol.[3]

Natural occurrences[]

o-Cresol is one of the chemical compounds found in castoreum. This compound is gathered from the beaver's castor glands and found in the white cedar consumed by the beaver.[4]

o-Cresol is a constituent of tobacco smoke.[5]

Production[]

Together with many other compounds, o-cresol is traditionally extracted from coal tar, the volatile materials obtained in the production of coke from coal. A similar source material is petroleum residues. These residue contains a few percent by weight of phenol and isomeric cresols. In addition to the materials derived from these natural sources, about two thirds of the Western world's supply is produced by methylation of phenol using methanol. The alkylation is catalysed by metal oxides:

C6H5OH + CH3OH → CH3C6H4OH + H2O

Over-methylation gives xylenol. Many other production methods have been examined, including oxidative decarboxylation of salicylic acid, oxygenation of toluene, and hydrolysis of 2-chlorotoluene.[3]

Applications[]

o-Cresol is mainly used as a precursor to other compounds. Chlorination and etherification gives members of a commercially important herbicides, such as 2-methyl-4-chlorophenoxyacetic acid (MCPA). Nitration gives dinitrocresol, a popular herbicide. Kolbe–Schmitt carboxylation gives o-cresotinic acid, a pharmaceutical intermediate. Carvacrol, essence of oregano, is derived by alkylation of o-cresol with propene. The muscle relaxant mephenesin is an ether derived from o-cresol.[3]

Health effects[]

Most exposures to cresols are at very low levels that are not harmful although, like phenols, cresols are skin irritants. When cresols are inhaled, ingested, or applied to the skin at very high levels, they can be harmful. Breathing high levels of cresols for a short time results in irritation of the nose and throat. Aside from these effects, very little is known about the effects of breathing cresols at lower levels over longer times. The acute LD50 for oral ingestion by mice is 344 mg/kg.[3]

References[]

  1. ^ a b c d NIOSH Pocket Guide to Chemical Hazards. "#0154". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ "Cresol (o, m, p isomers)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  3. ^ a b c d Helmut Fiegein "Cresols and Xylenols" in Ullmann's Encyclopedia of Industrial Chemistry" 2007; Wiley-VCH, Weinheim. doi:10.1002/14356007.a08_025
  4. ^ The Beaver: Its Life and Impact. Dietland Muller-Schwarze, 2003, page 43 (book at google books)
  5. ^ Talhout, Reinskje; Schulz, Thomas; Florek, Ewa; Van Benthem, Jan; Wester, Piet; Opperhuizen, Antoon (2011). "Hazardous Compounds in Tobacco Smoke". International Journal of Environmental Research and Public Health. 8 (12): 613–628. doi:10.3390/ijerph8020613. ISSN 1660-4601. PMC 3084482. PMID 21556207.

External links[]

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